Extracting a URL in the query part of another URL

Question

How can I extract a valid URL from a string like this one

h*tps://www.google.com/url?q=h*tp://www.site.net/file.doc&sa=U&ei=_YeOUc&ved=0CB&usg=AFQjCN-5OX

I want to extract this part: h*tp://www.site.net/file.doc, this is my valid URL.

What do you mean with valid? Do you wont to replace the "*" with a "t" or what else? — FeliceM, May 12 '13 at 08:50
Regex is the right way to go. Define the pattern that you want to extract, get the Regex's Matches and pick the one that you require. — Saravanan, May 12 '13 at 08:50
FeliceM, i replaced the t by the star because of the restriction of posting more than two link.. i'm new here! Thank you anyway this informationn can be usefull to me. — Naourass Derouichi, May 12 '13 at 09:03
I believe the removal of the * changes what possible solutions are available therefore the * should be included in the question. — Ash Burlaczenko, May 13 '13 at 10:42

score 5 · Accepted Answer · answered May 12 '13 at 09:50

5

Add System.Web.dll assembly and use HttpUtility class with static methods. Example:

using System;
using System.Web;


class MainClass
{
    public static void Main (string[] args)
    {
        Uri uri = new Uri("https://www.google.com/url?q=http://www.site.net/file.doc&sa=U&ei=_YeOUc&ved=0CB&usg=AFQjCN-5OX");
        Uri doc = new Uri (HttpUtility.ParseQueryString (uri.Query).Get ("q"));
        Console.WriteLine (doc);
    }
}

answered May 12 '13 at 09:50

Denis

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With the protocol as `h*tps`, would `Uri` parse the string correctly? – Ash Burlaczenko May 13 '13 at 10:42
Uri parse the string correctly. – Denis May 13 '13 at 11:28
Thats incorrect, tested and got an `Invalid URI: The URI scheme is not valid.` exception. – Ash Burlaczenko May 13 '13 at 15:36
Whick version of .net/mono? – Denis May 13 '13 at 15:45
5, the version is irrelevant, the class hasn't changed. `h*tps` is not a valid protocol so how could it parse it? – Ash Burlaczenko May 13 '13 at 15:59

score 1 · Answer 2 · answered May 12 '13 at 09:40

1

I don't know what your other strings can look like, but if your 'valid URL' is between the first = and the first &, you could use:

(?<==).*?(?=&)

It basically looks for the first = and matches anything before the next &.

Tested here.

answered May 12 '13 at 09:40

Jerry

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Virus · Answer 3 · 2013-05-12T09:59:17.960

1

You can use split function

    string txt="https://www.google.com/url?q=http://www.site.net/file.doc&sa=U&ei=_YeOUc&ved=0CB&usg=AFQjCN-5OX";

    txt.split("?q=")[1].split("&")[0];

edited May 12 '13 at 09:59

answered May 12 '13 at 09:44

Virus

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There are still a bunch of garbage behind. – nhahtdh May 12 '13 at 09:46
ok. You can use so: 'txt.split("?q=")[1].split("&")[0];' – Virus May 12 '13 at 09:53
1

Please edit it into your post. – nhahtdh May 12 '13 at 09:55

score 0 · Answer 4 · answered May 12 '13 at 09:35

0

in this particular case with the string you posted you can do this:

string input = "your URL";
string newString = input.Substring(36, 22) ;

But if the length of the initial part of the URL changes, and also the lenght of the part you like to extract changes, then would not work.

answered May 12 '13 at 09:35

FeliceM

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this is also usefull thanks: – Naourass Derouichi May 12 '13 at 09:39
You can replace the numbers (36, 22) with int variables and fix the value counting the character to a certain occurrence. My answer is very basic. – FeliceM May 12 '13 at 09:40
@NaourassDerouichi: Please use the Uri class and ParseQuery utility to process the URL. – nhahtdh May 12 '13 at 09:44

Extracting a URL in the query part of another URL

4 Answers4